In this study, X-ray detectors with coplanar metal-semiconductor-metal structure, were fabricated employing high quality chemical vapour deposited (CVD) diamond film grown by a direct current arc jet plasma system. In which the electrical contacts with dimension of 25 µm in width with a 25 µm inter-electrode spacing, were patterned on the growth side of the diamond film using lift-off technology. The performance of the fabricated detectors was evaluated by steady-state X-ray illumination. The photoconductivity of the diamond detectors was found to linearly increase with increase in the X-ray photon flux. This demonstrates that high quality CVD diamond can be used for X-ray detectors.